#pragma glslify: circle = require(glsl-2d-primitives/circle)
#pragma glslify: rectangle = require(glsl-2d-primitives/rectangle)
#pragma glslify: polygon = require(glsl-2d-primitives/polygon)

attribute vec2 vUv;
uniform sampler2D map;

void main() {
    gl_FragColor = texture2D(map, vUv);
    // Mask the image with a centered rectangle
    gl_FragColor.a = rectangle(vUv, vec2(0.4, 0.6));

    // Draw a pentagon, without alpha masking
    gl.FragColor = vec4(vec3(polygon(vUv, 0.4, 5.0)), 1.0);

    // Mask the image with a ring, combining 2 circles
    float ring = circle(vUv, 0.5) * (1.0 - circle(vUv, 0.52));
    gl_FragColor.a = ring;
}